Because elastomers can be used in sealing applications, it is important that the elastomers perform well under compression. Compressive sealing is based on the ability of an elastomer to be easily compressed and develop a resultant force that pushes back on the mating surfaces. The ability of a material to maintain this resultant force as a function of time over a range of environmental conditions is important to long term stability. As a result of thermal expansion, stress relaxation and thermal aging, the initial sealing forces will decay over time. By determining the retained sealing force, elastomeric materials can be evaluated for their sealing force retention under a range of conditions.
Cured fluoroelastomers (also known as FKM's, or fluorocarbon elastomers containing vinylidene fluoride and hexafluoropropylene) are particularly useful as seals, gaskets, and molded parts in systems that are exposed to elevated temperatures and/or corrosive materials, such as in automotive, chemical processing, semiconductor, aerospace, and petroleum industry applications, among others. For sealing applications that require resistance to the most extreme conditions, cured perfluoroelastomers are used. However, cured perfluoroelastomers (also known as FFKM's or cured perfluorocarbon elastomers) traditionally have shown poor retained sealing force as compared to conventional FKM or FKM compounds.